Heretofore, X-ray images were taken using a film which is responsive to X-rays, and then developing the film. This technique has a number of problems. The X-ray film must be stored and handled under conditions where it is not subjected to light. Also, it requires a period of time after the image is taken to develop the film. Since it cannot be determined whether a satisfactory image has been taken until after the film is developed, this often causes a delay for the parties involved, particularly if the X-ray picture is of a person. Also, the image is read as a negative of the film and not a positive. Therefore, it is difficult to obtain additional copies of the X-ray image. In addition, an X-ray film can be used only once. This adds to the cost of taking X-ray image and requires the maintenance of a large supply of X-ray films. In addition, it is difficult to digitize and/or transmit a film X-ray.
Some dental X-ray sensor systems advertised use a charge coupled device (CCD) as a sensing element. An example of such a system is the "VISUALIX" system by Philips Medical Systems of Philips. The CCD is typically encapsulated in an opaque housing and electrical wires connect the CCD to a base station which is typically powered by 110 or 220 volts a.c. In operation, the housed CCD is placed in the mouth of a person next to a tooth which is to be X-rayed. The base station contains control circuitry and readout circuitry for powering up the CCD and then for reading out an image formed in the CCD by an X-ray passing through teeth. The creation of an electronic image facilitates its being digitized and transmitted such that it can be read at a remote location from where it was generated. In order to avoid causing an electrical shock to the person whose X-ray is being taken, it is required to provide electrical isolation between line voltage powering the base station and the CCD. It is also required to have voltage overload protection provided in the base station in case of a voltage or current spike in the a.c. power source. The CCD sensor and the wires attached thereto have to be sterilized after each use to limit the spread of infection. This is difficult to do because the wires are connected at both ends and must be disconnected or the entire base station, wires, and CCD sensor must all be sterilized. Another problem is that it is an annoyance to the person whose X-rays are being taken to have wires extending from his or her mouth.
It is desirable to have a dental X-ray system which uses a CCD sensor that can be placed in a persons mouth without the need for it being connected by electrical wires to a base station during the taking of an X-ray.